I wanted to use the QSYNC app on my Pixel phone to sync new camera images to my Windows PC.
Initially, it works fine, but then I noticed it uploads a large hidden file, in addition to the small image file, and that takes a long time, also costing data. The unwanted file is DCIM\.thumbnails and this file is updated after each new image is taken, thus also synced.

I need QSYNC to skip this unwanted file. It is a dotted file, so it has the same class as a hidden file, but I can skip those attributes.